Skip to main content
Ch. 1 - Trigonometric Functions
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
2장, 문제 50

Concept Check Suppose that the point (x, y) is in the indicated quadrant. Determine whether the given ratio is positive or negative. Recall that r = √(x² + y²) .(Hint: Drawing a sketch may help.) I , r/y

검증된 단계별 안내
1
Identify the quadrant given in the problem, which is Quadrant I. In this quadrant, both x and y coordinates are positive, so \(x > 0\) and \(y > 0\).
Recall the formula for \(r\), the distance from the origin to the point \((x, y)\): \(r = \sqrt{x^2 + y^2}\). Since \(x^2\) and \(y^2\) are always non-negative, \(r\) is always positive.
Analyze the ratio given: \(\frac{r}{y}\). Since \(r > 0\) and \(y > 0\) in Quadrant I, both numerator and denominator are positive.
Because both numerator and denominator are positive, the ratio \(\frac{r}{y}\) must be positive.
To confirm your understanding, sketch the coordinate plane, plot a point in Quadrant I, and visually verify that \(r\) and \(y\) are positive, reinforcing why the ratio is positive.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
2m
도움이 되었나요?

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Coordinate Plane Quadrants

The coordinate plane is divided into four quadrants, each with specific signs for x and y coordinates. In Quadrant I, both x and y are positive, which affects the sign of ratios involving these values.
추천 영상:
6:36
Quadratic Formula

Distance from Origin (r)

The distance r from the origin to a point (x, y) is given by r = √(x² + y²), which is always positive. This value represents the radius in polar coordinates and is crucial for understanding ratios involving r.
추천 영상:
6:58
Convert Points from Rectangular to Polar

Sign of Ratios Involving Coordinates

The sign of a ratio like r/y depends on the signs of numerator and denominator. Since r is always positive, the sign of r/y depends solely on y's sign, which varies by quadrant, helping determine if the ratio is positive or negative.
추천 영상:
05:32
Intro to Polar Coordinates